40 amp portable and adjustable open EVSE for $500

Over the weekend I bought a 40 amp capable open-EVSE from GlennD over at the Leaf forum. He had actually put it together as a 30 amp EVSE (what you see in the pictures), but he was able to quickly add a 40 amp contactor, and I provided my own 50 amp J1772 cable and 14-50 plug. The EVSE has a button that allows setting any amperage from 6-40 in 2a increments, and also has a built-in timer (but who needs that with RavCharge! ) The total cost came to about $500. The only downsides are that it's 240v only, and I'm not sure how waterproof the case is. But 120v capability could be easily done with a different choice of contactor (Glenn used a contactor that he just happened to have lying around for my very short-notice mod), and a different choice of case could ensure full waterproofing.

I'd been looking for a long time for a portable and adjustable 40 amp EVSE that I can use at 24 amps in my garage plugged into my 30 amp dryer outlet, and take on the road to use at 40 amps at RV parks and the like, and also dial down to 12-16 amps to use with my quick220 at a friend's if need be. Sadly there's no retail EVSE you can buy that can do these things.

I love what Tony's doing with the Tesla UMC (Jesla), but the price tag is really steep, and you don't get full adjustability. You can buy a bunch of $45 Tesla adapters for limited adjustability, but some settings are still missing. Also I'm a little spooked by the awkward design of the plug on the UMC and the reliability issues resulting from that reported by some Tesla drivers. An EVSE-upgraded 2013 Leaf EVSE is also a nice option that offers full adjustability in a very small package, but it can only do up to 25 amps (and that's if you're willing to "overclock" it beyond the 20 amp rating of its 12ga wire and 20amp handle.)

So anyway, I concluded that there's really no option that can do everything I want except to build an open-EVSE. I've been researching it for a while, but the problem is most of the example builds out there are only capable of 30 amps. I could've figured it out eventually and built one myself, but Glenn's built a bunch of open-EVSEs and has got it wired, and he crafted the unit with excellent build quality. Just wanted to let others know that this option's out there.

The reason there is not one on the market is pure economics and utility. Only the Rav takes advantage of a 40A EVSE and a Tesla is supplied with a cord. In addition there are few 50A 240V outlets out there making the utility of a mass produced cord very low. A properly manufactured 40A cord that can endure frequent use and abuse is going to be heavy and not exactly small. "Movable" and Portable" require different levels of engineering and most will be doing this charging at stationary locations with the proper service.

Cool FoolJoe. The only feature that would make it better would be to add a J1772 receptacle to the side to make it a pass through device (a.k.a. charging station extension cord). Since you already are carrying around 10-20 ft of cord, it would be nice to use it in a pinch to extend a cord that is too short in a parking space. Safety concerns of having live tips be exposed when using it as a regular EVSE could be alleviated by using a simple contactor close the "extension port input pins" when it senses a J1772 connector is attached.

4EVEREV said:

The reason there is not one on the market is pure economics and utility. Only the Rav takes advantage of a 40A EVSE and a Tesla is supplied with a cord. In addition there are few 50A 240V outlets out there making the utility of a mass produced cord very low. A properly manufactured 40A cord that can endure frequent use and abuse is going to be heavy and not exactly small. "Movable" and Portable" require different levels of engineering and most will be doing this charging at stationary locations with the proper service.

Click to expand...

The 40A capability is only one part of the "ideal" EVSE I described - full adjustability is the biggest missing feature out there, and there's absolutely no good reason for it (it's just software.) Along those lines is another very strange gaping hole in the EVSE market - there's not a single EVSE available that can run at 24A out of the box (ok there was the SPX PowerXpress, but it has compatibility issues), while a 30A outlet (e.g. an electric dryer outlet) is probably the most likely 240V outlet to be available in homes for charging purposes.

As far as the 40A vs 30A question, realize that for the first ~2 years of widespread EV availability, when the Leaf and Volt first came out in 2011, both of these cars were only capable of charging at 16A, yet the vast majority of EVSEs installed were 30A. Clearly people can see the value of a little "future-proofing", even if the Rav is currently the only EV capable of charging at that level that doesn't have an included EVSE. And it's not like 30A is some magical limit beyond which manufacturing or engineering costs would skyrocket - you just need 8ga wire instead of 10ga, and a slightly bigger contactor or relay. It's not that hard - Glenn converted my EVSE from 30A to 40A overnight.

Kohler Controller said:

Cool FoolJoe. The only feature that would make it better would be to add a J1772 receptacle to the side to make it a pass through device (a.k.a. charging station extension cord). Since you already are carrying around 10-20 ft of cord, it would be nice to use it in a pinch to extend a cord that is too short in a parking space. Safety concerns of having live tips be exposed when using it as a regular EVSE could be alleviated by using a simple contactor close the "extension port input pins" when it senses a J1772 connector is attached.

Click to expand...

You can buy or make an adapter like this that can turn any portable EVSE into a "J1772 extension cord."

fooljoe said:

Kohler Controller said:

Cool FoolJoe. The only feature that would make it better would be to add a J1772 receptacle to the side to make it a pass through device (a.k.a. charging station extension cord). Since you already are carrying around 10-20 ft of cord, it would be nice to use it in a pinch to extend a cord that is too short in a parking space. Safety concerns of having live tips be exposed when using it as a regular EVSE could be alleviated by using a simple contactor close the "extension port input pins" when it senses a J1772 connector is attached.

Click to expand...

You can buy or make an adapter like this that can turn any portable EVSE into a "J1772 extension cord."

Click to expand...

Actually, I was just thinking of adding the socket to the side of the box.
http://modularevpower.com/Coupler%202.htm
Which would also act as a plug holder while not being used.

fooljoe said:

The 40A capability is only one part of the "ideal" EVSE I described - full adjustability is the biggest missing feature out there, and there's absolutely no good reason for it (it's just software.) Along those lines is another very strange gaping hole in the EVSE market - there's not a single EVSE available that can run at 24A out of the box (ok there was the SPX PowerXpress, but it has compatibility issues), while a 30A outlet (e.g. an electric dryer outlet) is probably the most likely 240V outlet to be available in homes for charging purposes.

Click to expand...

According to a fellow member here (to whom I sold my SPX Power Express to use on his VOLT) there is a firmware update to resolve the incompatibility issue with the RAV4 EV, and it does indeed support 240V at 24A, perfect for an electric drier 30A outlet application. It is also one of the EVSE L2 products available that is more conducive to "portability".

Kohler Controller said:

Actually, I was just thinking of adding the socket to the side of the box.
http://modularevpower.com/Coupler%202.htm
Which would also act as a plug holder while not being used.

Click to expand...

Yeah, I know what you mean. That would be pretty cool - it's just a question of whether it would be easier to add the necessary relays and stuff to make it work inside the box or just go with a self-contained unit like I linked to. The other advantage of a self-contained unit is you can plug anything you want into it - I saw a pic a while back of a van-dweller using one to plug in his van at a free charging station...

Dsinned said:

According to a fellow member here (to whom I sold my SPX Power Express to use on his VOLT) there is a firmware update to resolve the incompatibility issue with the RAV4 EV, and it does indeed support 240V at 24A, perfect for an electric drier 30A outlet application. It is also one of the EVSE L2 products available that is more conducive to "portability".

Click to expand...

That's good to know about the update. I really like the look and feature set of this EVSE, and actually gave some serious consideration to getting it back when I first got my Leaf, but I read that it had compatibility problems with the Leaf's timer. Hopefully they've resolved all that now, but according to the one review on amazon it's got other problems too... (I guess it's Bosch now instead of SPX, don't know if that affects anything or not.)

fooljoe said:

Kohler Controller said:

Actually, I was just thinking of adding the socket to the side of the box.
http://modularevpower.com/Coupler%202.htm
Which would also act as a plug holder while not being used.

Click to expand...

Click to expand...

Yeah, I know what you mean. That would be pretty cool - it's just a question of whether it would be easier to add the necessary relays and stuff to make it work inside the box or just go with a self-contained unit like I linked to. The other advantage of a self-contained unit is you can plug anything you want into it - I saw a pic a while back of a van-dweller using one to plug in his van at a free charging station...

I see what you mean now. I guess it was the $245 that threw me off.